Upgrade chroma to v2.3.0 (#21259)

The behaviour of `PreventSurroundingPre` has changed in
https://github.com/alecthomas/chroma/pull/618 so that apparently it now
causes line wrapper tags to be no longer emitted, but we need some form
of indication to split the HTML into lines, so I did what
https://github.com/yuin/goldmark-highlighting/pull/33 did and added the
`nopWrapper`.

Maybe there are more elegant solutions but for some reason, just
splitting the HTML string on `\n` did not work.

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/markup/orgmode/orgmode.go

@@ -17,8 +17,8 @@ import (
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/util"
 
-	"github.com/alecthomas/chroma"
-	"github.com/alecthomas/chroma/lexers"
+	"github.com/alecthomas/chroma/v2"
+	"github.com/alecthomas/chroma/v2/lexers"
 	"github.com/niklasfasching/go-org/org"
 )